The invention concerns a gear set. In particular, the present invention relates to a gear set for differential gear shafts of internal combustion engines. The gear set includes at least one first toothed wheel, which is rotatable around an axle fixed to a housing and meshes with a second toothed wheel which can be moved parallel to its axis during assembly in order to adjust backlash.
It is known that backlash, more particularly circumferential backlash, serves to form a hydrodynamic lubrication, to compensate for mass changes as a result of temperature influences, for tooth deformation resulting from stress, and for manufacturing and assembly errors.
Thus known from DE-B 1 180 596, for example, is a gear set with a device for setting the backlash in which conical toothed wheels are shifted axially in opposition to each other depending on certain parameters of the gear set, and thus the backlash can be set depending, for example, on rotational speed, temperature, or load.
In a further backlash adjustment in spur-wheel gears with axially movable wheels it is provided according to DE-OS 2 020 722 that the teeth are to be configured so as to be wedge-shaped so that backlash can be set with an axial movement of one wheel.
Further known from DE-PS 883 379 is a rack and toothed-wheel-segment gear set in which in one of the end positions, a spacer similar to a tooth face is provided at least on one tooth face in order to eliminate backlash.
From the German textbook Maschinenelemente (Machine elements), Vol. II, 2nd edition, by Niemann and Winter, page 365 and following, it is further known that by copper plating the teeth of a toothed wheel, backlash can be brought for practical purposes to zero.
Finally, it is known, by way of example, as a frequent suggestion for a backlash adjustment according to DE-PS 650 754 to bear one of the shafts of the meshing toothed wheels in an adjustable eccentric bushing which is fixed relative to the housing upon realization of the desired backlash.
Finally, eccentric elements also serve in the gear set for differential gear shafts of an internal combustion engine according to DE 197 50 286 A1, whereby in order to adjust backlash between a first, crankshaft-side toothed wheel and an intermediate wheel or a second wheel which is born in a bearing frame of the differential gear shaft and which already meshes with a drive wheel of the differential gear shaft, it is provided that the bearing frame is arranged so as to be movable and fixable for setting backlash by means of eccentric elements relative to the remaining machine housing. With this arrangement, backlash can be set only between two toothed wheels.
The object of the invention is to provide, for a gear set of the type described above, a relatively simple adjustment of backlash without repeated measurement of the backlash with purposeful movement of a wheel shaft on the one hand and without an expensive mechanical device on the other.
This object is achieved in the present invention by the use of a spacer which is removably arranged between the tooth faces of interfacing teeth of the meshing toothed wheels which serves the purpose of adjusting the backlash. Since the second toothed wheel can be adjusted with a predetermined force to the first toothed wheel, the spacer can be arranged without play between corresponding tooth faces of the toothed wheels.
With the invention, pairs of toothed wheels of a gear set can be adjusted in advantageous manner with respect to play.
According to the various embodiments of the present invention, the spacer can be a film of a synthetic or a metal, and a film-like thin wire mesh appears also to be suitable. In addition, the spacer can be configured as a layer of a galvanically deposited solid lubricant which is abraded off during operation of the gear set. The spacer can also be formed by means of spring tabs which are arranged on one side in the tooth spaces and which, fastened to a strap, form a comb strip. The thickness of the spacer at a given time, supplied in a tooth gap on two sides or on one side, is preferably selected such that a total circumferential backlash of 20 μm to 120 μm is achieved.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.